There has been explosive growth in the use of portable electronic devices, such as, pagers, cellular telephones, media players, and personal digital assistants. Along with this growth has been an ever-increasing trend towards miniaturizing the portable electronic devices while simultaneously increasing the number of features on the portable electronic devices. This increase in features includes combining features from various different types of devices, such as, cellular telephones and media players.
One result of this miniaturization trend has been the reduction in the size of the batteries used to power the electronic devices. The reduced battery sizes have reduced the length of time the electronic devices are useable between charges.
In an effort to further reduce the sizes of the electronic devices, U.S. Pat. No. 6,252,336 to Hall proposes a scheme to replace the silent or vibrating alarm mechanism found in some portable electronic devices with a smaller piezoelectric device. In addition, Hall discloses that the piezoelectric device includes a mass, in which, mechanical movement of the mass, as caused by movement of the electronic device, is converted into electrical energy and used to recharge a battery. Because piezoelectric devices typically require high frequency movements, it appears that the electronic device disclosed in Hall would have to be moved relatively rapidly in order to generate any appreciable amounts of electrical energy. In other words, users would most likely be required to consciously move the electronic device to recharge the battery. In addition, the replacement of conventional vibrating mechanisms with the piezoelectric devices will, in most likelihood, be a relatively complicated process which significantly adds to the costs associated with manufacturing the electronic devices.
It would therefore be beneficial to be able to recharge the batteries without the additional costs and burdens associated with the piezoelectric device proposed by Hall.